Freely slidable paraffin scraping and removing tool for cleaning oil well tubing

ABSTRACT

A simple cylindrical paraffin scraping tool adapted to slidably ride up and down between spaced apart stop means on a sucker rod to scrape and remove hardened paraffin and similar deposits from the interior walls of oil well tubing with the scraping tools stored in operative readiness within the well during pumping of the oil well so that the scraping apparatus is immediately available when it becomes necessary to clean the well. Some minor preventive maintenance may be performed during continued pumping of the oil well by incidental agitation of the scrapers preventing and slowing the formation of deposits in the oil well tubing but the principal scraping operation occurs when and as the sucker rod line and attached plurality of scraper tools are pulled out of the well for periodic pump changes.

United States Patent Hellums et al.

[ FREELY SLIDABLE PARAFFIN SCRAPING AND REMOVING TOOL FOR CLEANING OILWELL TUBING Oct. 14, 1975 3.364998 1/1968 Sable 166/176 X 221 Filed:Dec. 17, 1973 5 [57] 7 ABSTRACT A simple cylindrical paraffin scrapingtool adapted to [21] Appl' 42s295 slidably ride up and down betweenspaced apart stop means on a sucker rod to scrape and remove hardened[52] US. Cl. 166/175; 166/ 176; 308/4 A paraffin and similar depositsfrom the interior walls of [51] Int. CL? .l E21B 37/02 oil well tubingwith the scraping tools stored in opera- [58] Field of Search 308/4 A;166/175, 176, tive readiness within the well during pumping of the166/170 oil well so that the scraping apparatus is immediately availablewhen it becomes necessary to clean the well. [56] References Cited Someminor preventive maintenance may be per- UNITED STATES P S formed duringcontinued pumping of the oil well by 1,758,995 5/1930 Armstrong et a1.166/175 incilemal l l of the f P pwjveming f 1 995,095 3/1935Fitzpatrick 308/4 A X slowing the format1on of deposits 1n the 011 welltubing 2,563,038 8/1951 lrwin 166/175 x but the Principal ScrapingOperation Occurs when and 2,997,106 8/1961 Tripplehorn 166/176 as theSucker rod line and attached plurality of scraper 3,083,772 4/1963 Triplehom.... 166/ 176 tools are pulled out of the well for periodic pump3,141,505 7/1964 Tripplehorn.... 166/176 X h 3,273,648 9/1966 Barnard166/175 3,330,359 7/1967 Ward 166/176 X 3 Claims, 4 Drawing Figures r Ir z I x f y 1 I fi l 1| K l 7 x 9 US. Patent OCL 14, 1975 Sheet 1 133,912,007

US. Patent Oct. 14, 1975 Sheet 2 of3 3312907 US. Patent Oct. 14, 1975Sheet 3 of 3 3912 007 L FIG /4 30 g9 52 KP 36 w Y I I Q 54L 34.

'62 I I l FIG. 12

SUBJECT MATTER OF. THE INVENTION 5 This invention relates generally totools and equipment for scraping and removing paraffin from the interiorwalls of oil well tubing and relates more specifically to oil wellparaffin scraping'and removing tools and apparatus that can be stored insemi-passive state within IO the'oil well during pumping to be availablefor immediate use when needed with minimum interruption of pumpingoperations.

THE PRIOR ART Most crudeoil contains varyingamounts of paraffin andoccasionally asphalt particles which tend to become deposited on theinterior walls of the tubing employed in oil wells. In order to maintainpumping production from wells in which obstructions of paraffin and orasphalt particles have been deposited on the walls of the tubing it isnecessary from time to time to scrape and remove said deposits. In someinstances this is done by periodically employing expensive andcomplicated paraffin scraping and removing tools which are usuallyattached to and pushed through the oil well tubing by the sucker rodsemployed in theoil well. This is acomplicated operation requiring theremoval of the sucker rod string for insertion of the paraffin scrapertool or tools with operation of the well being interrupted from one toseveral days while the expensive scraper tools are inserted into thewell, the scraping operation completed and then removed. The extra work,expense and production interruption can prove prohibitively expensive inthe case of so called low quality oil wells. When the build up ofexceptionally sticky paraftin and asphalt becomes excessive and provestoo difficult for removal by ordinary tools it becomes necessary to pullthe tubing string out of the oil well and burn the tubing in order tomelt the obstructing deposits of paraftin and asphalt out of theinterior of the tubing pipes. This later procedure of pulling the tubingstring may involve'an interruption of production extending over severalweeks at very great expense.

There has been an abundance of prior patent art proposals for specialcomplicated tools with a number of the tools being commerciallyavailable-usually on a temporary lease or rental basis. By far and largethe tools'that have been proposed that are simple in construction andlow in expensiveness have failed to work satisfactorily while thecomplicated tools have often involved expensive outlays that wereexcessive for'rehabilitation of marginal low grade wells. There hastherefore been a long continuing need for a very simple durableparaffinscraping and removal tool that is so inexpensive incest and soindestructible in structure as to permit the tool to remain in placesemi permanently concurrently with continued pumping production of thewell.

OBJECTS OF THE INVENTION- volved in pulling the oil well tubing forcleaning purposes.

Another object of the invention is to devise an inexpensivelymanufactured and nearly indestructable paraffin scraping tool that willhave no moving parts to break off, that will be so impervious to wear bysemi permanent installation and usage as to make it practical for theoperator. to install a plurality of said paraffin scraping tools in anoil well and leave them in place.

Still another object of the invention is to devise a paraffm scrapertool that can be left in the well semi permanently during pumpingoperations so as to provide continuous agitation and scraping action inorder to prevent the build up of paraffin or asphalt deposits beforestubborn tenacious deposits have formed.

To the extent that it may be necessary for the paraffin scraperrecommended herein to operate in conjunction with a valve or seat valve,it is an object of this invention to devise and employa valve structurehaving minimum possibility of sticking and a valve design that can beoperated from the surface when necessary.

It is an object of this invention to devise a paraffin scraper tool thatcan rise through a limited distance with the up-flow of oil through theoil well tubing or by gravity fall by its own weight through a limiteddistance but with means for supplemental hammer driving of the scrapertool by lifting or dropping the weight of the sucker rod line through anextended piston stroke so as to drive the upper and lower stop meansagainst the top or the bottom of the scraper tool.

Still a further object of the invention is to devise a paraffin scrapingtoool of such substantial structure as to have use-value in hammeringout dents in the walls of the oil well tubing by using the weight of thesucker rod string to drive the scraper tool through the dented area inthe tubing.

These and other objects and advantages of this inven- 0 tion will becomeapparent through consideration of the following description and appendedclaims in conjunction with the attached drawings in which:

DESCRIPTION OF THE SEVERAL VIEWS IN THE DRAWINGS FIG. 1 is a perspectiveview of the top of the slidable paraffin scraping and removing tool.

FIG. 2 is a perspective view of the slidable paraffin scraping andremoving tool positioned on a sucker rod over the frusto-conical seatvalve within an oil well tubing.

FIG. 3 is a perspective view showing the bottom surfaces of thefrustro-conical seat valve and how it fits onto an oil well sucker rod.

FIG. 4 is a perspective view of the bottom of the slidable paraffinscraping and removing tool showing the concave arcuate cutting blade inthe underside of the lower ring of the tool.

FIG. 5 is a partial cut-away cross-section view of the lower annularparaffin cutting and scraping ring of the tool showing the nature of theconcave arcuate cutting blade.

FIG. 6 is a perspective view of how two slidable paraffin scraping andremoving tools may be spaced apart on successive sucker rods within anoil well tubing in relation to two frustro-conical seat valves and a rodbox I used as spaced apart stop means.

FIG. 7 is a perspective illustration showing how the slidable paraffinremoval tool meets the bottom of a rod box stop within the oil welltubing.

FIG. 8 is a perspective view of the slidable paraffin scraping andremoving tool as it fits on the top surface of the frustro-conical seatvalve within the oil well tub- FIG. 9 is a perspective drawing of analternate version of the slidable paraffin scraping and removing toolwhere the aligning and centering guide collar is a cone shaped extensionof the tubular casting of the paraffin scraping ring.

FIG. 10 is a perspective view of the top of another alternately stackedversion of the slidable paraffin scraping and removing tool where thetool is made from two different sizes of thick metal tubing.

FIG. 11 is a perspective drawing of a double ended version of theparaffin scraping and removing tool with the larger paraffin scraperrings on either end of the aligning connective guide collar with the topring showing the concave arcuate cutting blade.

FIG. 12 is an illustration of how another alternate version of thedouble ended paraffin scraping and removing tool works within the oilwell tubing and casing against two oppositely directed frustroconicalseat valves.

FIG. 13 is a perspective view of another double ended version of theparaffin scraping and removing tool with two smaller guide scrapingcollars on either end of a larger paraffin removing ring having aconcave arcuate cutting blade in the top surface.

FIG. 14 is a fragmentary perspective view showing a version similar tothat of FIG. 11 arranged on a sucker rod.

In describing one selected form or preferred embodiment of thisinvention as shown in the drawings and described in this specification,specific terms and components are used for clarity. However, it is notintended to limit the claimed invention to the specific form, componentsor construction shown and it is to be understood that the specific termsused in this illustration of the invention are intended to include alltechnical equivalents which operate in a similar manner to accomplish asimilar purpose.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION Referring tothe specific embodiment of the invention selected for illustration inthe accompanying drawings, the freely slidable paraffin scraping andremoving tool as illustrated in FIG. 1 is designated generally or as awhole by the number 21. Said freely slidable paraffin scraping andremoving tool 21 has an annularly shaped paraffin cutting and scrapingring 22 that is of such size and has an exterior circumference 23designed to fit snugly into the interior of one of the standard sizes ofoil well tubing so that its outside circumference will rub or scrapeagainst the walls of the tubing as said scraping tool falls or is pushedthrough the tubing. The size and thickness of paraffin scraping andcutting ring 22 serves in part as a weight affecting the rate of fall ofthe tool within the oil well tubing and this scraping and cutting ring22 can be increased in length to form a skirt ring like that illustratedin FIG. 9 and FIG. 10 in cases where additional strength or weighting isneeded. The interior circumference 24 of paraffin scraping ring 22 is ofsufficient diameter to permit the passage of a standard size sucker rod.32through'the center of said scraper ring and leave sufficientadditional open space said co-axially mounted sucker rod 32 and theinterior circumference 24 of the scraper ring to permit crude'oil anddislodged mud, paraffin and asphalt particles to. pass between thesucker rod and the interior walls 24 and scraper ring 22. The forwardscraping edge surface of scraper ring 22 may be left blunt on somescraper tools as implied in FIG. 1 or may be provided with a cuttingedge or blade 37 cut into the forward surface of cutting ring 22 asillustrated in FIGS. 4 and 5 of Drawings.

At a spaced apart distance above the paraffin scraping ring 22 there isprovided an upper annularly shaped aligning and centering guide collar25 having a guide collar outside circumference surface 26 that isdistinctly smaller than the outside circumference 23 of scraping ring 22leaving room for crude oil and paraffin particles to pass between guidecollar 25 and the interior walls of oil well tubing 30. Through thecenter of guide collar 25 there is provided a centering guide holeaperture 27 that maintains scraper tool 21 in parallel alignment betweenthe moving sucker rod 32 and the interior walls of oil well tubing 30.

Paraffin scraping ring 22 is held in spaced apart position from theupper annularly shaped aligning and centering guide collar 25 by meansof a plurality of circumferentially spaced apart spacer legs 2828 thatare formed by elongated metal bars of rectangular cross section arrangedin an inclined slope between the paraffin cutting and scraping ring 22and upper aligning and centering guide collar 25 as illustrated in FIGS.1, 2 and 4 in the Drawings herein. Said plurality of spacer legs 28 28are mounted in a circular arrangement such that the narrow side of eachof the spacer legs faces toward the outside circumference of saidscraper ring 22 and guide collar 25 leaving maximum open area exit flowports 29 29 between pairs of said spacer legs 28 28 so that crude oiland dislodged paraffin particles flowing upward through oil well tubing30 can freely pass through the central opening 31 within scraper ring 22and then out and up through the exit flow ports 29 29 between spacerlegs 28 28. Since said upper centering and guide collar 25 is distinctlysmaller than the inside diameter of oil well tubing 30 it is possiblefor the upward moving crude oil to flow around and past said guidecollar 25 without interruption of the oil flow.

A tubular guide hole aperture 27 is provided through the centerthickness of said aligning and centering guide collar 25 having adiameter slightly larger than the diameter of the sucker rod 32 beingemployed in the oil well and said paraffin scraper tool 21 is co axiallymounted at spaced apart intervals on the oil well string of sucker rods32 32 with each scraper tool 21 being free to slide up and down betweenadjacent pairs of spaced apart stop means 33 34 (FIG. 6). Both of saidstop means are mounted on a single length of sucker rod 32 and aparticular scraping tool 21 will therefore be limited to oscillating upand down between the particular pair of stop means 33 34 so that aplurality of such scraper tools 21 21 will be used on the sucker rodstring for a particular well to cover the tubing area where experienceindicates that paraffin deposits are most likely to occur. In mostinstances the upper stop means will usually be the joint coupling or rodbox 34 (FIG. 7) which is of sufficient size and strength to serve as ameans of employing the weight of the sucker rod line to hammer the uppershoulder of guide collar when it may be necessary to hammer driveparaffin scraper tool 21 through a particularly tenacious deposit ofparaffin or asphalt. Rod box 34 can be employed as a lower stop means inmany instances, but in more frequent situations a frustro conicallyshaped seat valve structure 33 will be employed as the lower stop means.Said frustro conical shaped seat valve structure 33 should be providedwith an outside diameter smaller than the insidediameter of oil welltubing so that crude oil can flow upward between the periphery of saidcone shaped seat valve stop structure and the walls of oil well tubing30. In addition, the upper surface of said cone shaped stop means 33should be shaped and adapted to fit or nest just into the concavearcuate cutting blade 37 of paraffin scraper ring 22 as shown in FIG. 8.This truncated frustro conical seat stop structure 33 has a tubularopening 35 vertically cut through conical seat stop structure 33 topermit said seat valve stop means to be concentrically mounted at aselected place on sucker rod 32. There is also provided an appropriatesecuring means 36 to permit said seat valve stop means 33 to be attachedto the sucker rod. It will be readily appreciated from examination ofthe drawings herein that the shape and size of said cone shaped seatvalve 33 will permit oil to flow upward around the edges of said valvebut that more solid particles of dislodged asphalt and paraffin willhave difficulty falling past cone shaped seat valve stop means 33 tolower depths in the well. When periodic complete cleaning of the wellrequires the pulling of sucker rod line 32 it will be apparent that, assaid sucker rod line 32 is pulled upward that seat valve 33 will bedriven into the center opening of scraper ring 22 virtually closing andsealing oil well tubing 30 so that all debris and particles of paraffinand asphalt will have to be driven ahead of the combined sweep of thescraper tool plus the closure of the seat valve into the scraper, tool.As said sucker rod line continues to be pulled the collected debris andparticles of asphalt and paraffin are pulled to the surface where theyspill out of the well.

It is the contention of these Inventors that said simplifled paraffinscraper tool 21 is novel and unique within itself as an inexpensive andnearly indestructable fool proof tool. However, the Inventor would alsoassert and argue that the combined system of the described paraffinscraper tool plus the associated use in connection with the sucker rodstring and reciprocal oscillation of a plurality of scraper toolsbetween specially shaped spaced apart stop means constitutes anapparatus system of unique versatility and utility.

It should be appreciated that once the utility of this simplified toolstructure is disclosed that a variety of functionally equivalentstructures can be improvised to perform the same functions in a similarmanner within the spirit and purpose of the invention. Under thecircumstances, the Inventor would like 'to illustrate the claimprotection for two of the more basic functionally equivalent toolstructures that he feels should be within the scope of the invention.

FIG. 9 of the Drawings herein illustrates the manner in which the basicfunctional features of the tool could be cast or machined from a unitarylength of metal bar material that would create a more presentable toolfree of welded joints that might break during hammering of the tool inthe oil well. Moreover, the employment of a smoother truncated coneshape for the upper portion of said unitary paraffin scraper tool 41reduces the dan ger of the tool hanging up in the well during theprocess of pulling the sucker rod line.

In this alternate version of the paraffin scraper tool contemplated bythese Inventors said paraffin scraper tool 41 has been provided with acutting ring 42 having an extended length or skirt in order to indicatethat the skirt length of said scraping ring 42 can be lengthened to theextent that may be needed in order to supply additional strength oradded weight when the modified tool is used to remove stubborn asphaltdeposits or when the tool is used to wedge and hammer out dents in thewalls of the oil well tubing. Except for the change in size, utility andweight caused by the increase in skirt length, modified scraper ring 42is the functional equivalent of scraper ring 22 in the preferred versionof the invention.

The major changes in this modified version of the invention relate tofabrication of the upper part of the modified paraffin scraper tool 41from a casting or machined unitarymetal body in which the upper portionof the tool takes the form of a truncated cone 42 continuous with andsetting on top of the cylindrically shaped tubular paraffin scrapingring. The upper annu-.

larly shaped aligning and centering guide collar 43 is spaced apart fromscraper ring 42 but iscast or machined as an integral or unitary part ofthe overall tool 41 with a tubular guide hole aperture 45 providedthrough said tubular aligning and centering guide collar 43. Into theface of the inclined portion of truncated cone 44 there is cut aplurality of open space apertures forming exit flow ports 46 46 whichpermit oil and dislodged paraffin particles to flow through the scrapertool and out via said exit ports 46 46. The portion of the materialremaining in the truncated portion of cone 44 after cutting out exitports 46 46 constitute a plurality of circumferentially spaced apartvertical spacer legs 47 47 interconnecting and separating paraffincutting and scraping ring 42 and aligning and centering guide collar 43.

With the exceptions already referred to above, the various parts of themodified unitary scraping tool 41, the various component parts ofunitary cone shaped scraper tool 41 have approximately the same relativesize and function as the equivalent parts of paraffin scraper 21 and noeffect will be made to further duplicate the descriptive materialalready set forth above. However, it should be expressly noted that whencone shaped scraper tool 41, or any of the equivalent scraper tools, isfabricated from heavy durable materials and is provided with an extendedheavy skirt scraping ring 42 as shown in FIG. 9 of the drawings that anadditional non scraping function of element of utility becomespossible.When a' minor cave-in or dent occurs in installed tubing and theoperator wants to hammer out or remove said dent, the operator can liftthe sucker rod line, which weighs several thousand pounds, and then dropthe combined weight of the sucker rod line so that such weight strikesor hammers on the upper shoulder of guide collar 43 until tool 41immediately above the cave in or dent is driven or hammered through thecaved-in spot in the oil well tubing until the caved-in spot isforcefully dialated or distended back to the approximate original shapeof the oil well tubing. This is a remarkably unique and usefulco-function not found in other oil well scraper tools. It should also bereadily apparent that the unitary scraper tool 41 illustrated in FIG. 4can be used in the system of apparatus previously described inconnection with the preferred version of the invention illustrated inFIGS. 1, 2 and 3 herein. When scraper tool 41 is to be used forhammering out dents and stubborn obstructions, scraping ring 42 shouldbe provided with blunt or square forward scraping edge but in someapplications it will be desirable to have an arcuate cutting edge, likethat illustrated in FIG. cut into the undersurface of said tubularscraping ring to provide both cutting and scraping action against theinside walls of the oil well tubing being cleaned.

A third basic alternate version 51 of the paraffin scraper tool claimedas part of this invention is illustrated in FIG. of the Drawings herein.This third version can be improvised or manufactured from two shortlengths of tubular pipe of selected diameter. Paraffin scraping ring 52is a selected length of tubular pipe of such exterior circumference andsize as to just barely fit into and frictionally engage and scrape theinterior walls of one of the standard sizes of oil well tubing. In thecase of this alternate version, however, the plurality ofcircumferentially and evenly spaced apart exit flow ports 56 56 are cutinto the upper portion of the length of tubular pipe from which scraperring 52 is fabricated with the remaining space and material aftercutting out exit ports 56 56 constituting circumferentially spaced apartvertical spacer legs 57 57 in continuing alignment with the interior andexterior tubular surfaces of said paraffin scraper ring 52. The upperannularly shaped aligning and centering guide collar 53 is fabricatedfrom a short length of metal tubular material of such circumferentialsize as to snugly fit into and just inside of the upper ends of spacedapart vertical spacer legs 57 57 as illustrated in FIG. 10 of theDrawings. The tubular pipe selected for upper guide collar 53 shouldhave an inside diameter or circumferential guide hole aperture 55 largerthan the diameter of the sucker rod being employed in the oil well.Except for the unusual appearance caused by stacking upper guide collar53 on top of scraper ring 52 and the simplified manner in which theplurality of circumferentially spaced apart vertical spacer legs 57 57are fabricated to separate and interconnect guide collar 53 and scraperring 52, the remainder of the structure of this stacked alternateversion of the paraffin scraper ring contemplated by this invention isso completely analogous to the equivalent parts of paraffin scraper tool21 as to not require further elaboration. It also follows that thisalternate stacked version of paraffin scraper 51 can also be used withthe previously described systems of oil well cleaning apparatus and thatparaffin scraper ring 52 can also be provided with an additional arcuatecutting blade cut into the undersurface of said tubular scraping ring 52like the blade illustrated in FIG. 5 of the Drawings to provide bothcutting and scraping action against the inside walls of the oil welltubing being cleaned.

The several alternate versions of the oil well paraffin scraper toolsdiscussed above are all designed for hammered brute force scraping ofstubborn paraffin and asphalt deposits from the walls of oil welltubing. There are instances, however, when the agitation caused byoscillation or reciprocal movement of a scraper tool during pumpingoperations as well as when the sucker rod string and attached scrapertools are being removed could contribute to prophylactic prevention ofdeposit built ups in the oil well tubing. It will usually be desirableto use one of the first three versions of the paraffin scraper tooldescribed herein at the well bottom end of the sucker rod string with acone shaped stop means 33 to close off and seal this last scraping andcleaning tool as the sucker rod string is pulled to the surface with allof the sludge and dislodged particles of paraffin and asphalt drivenahead of this last scraper tool. However, it would be useful for part orall of the slidable and fluctuating scraper toolsat the intermediatelevels of the well to be able to scrape and/or cut as they move eitherup or down.

The inventors therefore propose to manufacture a double ended version ofthe paraffin scraping tool. as illustrated in FIGS. ll, 12 and 13 of thedrawings herein. The double ended stacked tool disclosed in FIG. 11 isan expanded version of scraper tool 51 disclosed in FIG. 10 in which atubular cutting ring 62 62 is mounted on each end of tubular annularlyshaped aligning and centering connective guide collar 63 so that ascraping ring projects in each of the vertical directions. Except forstacking a cutting ring 62 on each end of connective central collar 63each of the parts in said double ended stacked paraffin scraper toolperform the same functions as the equivalent parts of single endedparaffin scraper tool 51 previously discussed. Each of said scraperrings 62 62 can be provided with a square or blunt forward scrapingsurface 68 as illustrated in FIG. 14 or alternatively each said scraperrings 62 62 can be provided with an arcuate cutting blade 69 69 cut intothe forward scraping surface of each of the double ended scraper rings62 62 to provide both scraping and cutting action against the insidewalls of the oil well tubing being cleaned. When the alternate structuredisclosed in FIG. 11 is employed for the paraffin scraper tool, and itproves desirable to drive or hammer the scraping tool to some extent itwill prove desirable to use connective rod box 34 34 as both the upperand lower stop means. Note that FIG. 14 of the Drawings illustrrates howsucker rod string 32 and connective rod box 34 can be driven through thetubular opening in scraper ring 62 to strike and hammer on the shoulderend of central connective collar 63 and either end of connective collar63 can be hammered by an upper and lower rod box stop means 34 to drivethe scraper tool either up or down.

Another alternate version of a double ended paraffin scraper employingthe inventive features of this invention is illustrated in FIG. 13 anduse or application of this double ended scraper tool as an intermediatescraper is illustrated in FIG. 12. In this instance the primary cuttingor scraping surfaces are built into the port openings 74 74 of a largedouble ended scraper ring 72 while a pair of aligning and centeringcollars 73 73 are mounted within extended spacer legs 77 77. The top andbottom ends of the pair of centering collars 73 73 can be left blunt toscrape larger deposits of paraffin and asphalt off of sucker rod 32 asillustrated in FIG. 13 and driven or hammered by rod box stop means 3434 or .the forward ends of centering collars 73 73 may be provided witharcuate cutting blades cut into the forward end surface of the centeringcollars 73 73. The principle utility of this alternate version of thedouble ended paraffin scraping tool will be found in employing either ofthe double ended scraper tools at intermediate levels in oil wells asillustrated in FIG. 12. FIGS. 11 and 13 show the double endedscrapertools alone while FIG. 12 illustrates an application of a double endedscraper tool at an intermediate level in a system of apparatus forscraping and cleaning oil well tubing. The elements and functions ofthese double ended'scrapers as a part of a system of apparatus forcleaning oil well tubing is so clearly analogous to the equivalentelements and functions in the previous versions of this invention thatthere should be no need to repeat these now obvious explanations at thispoint.

OPERATION In actual operation a pluralilty of any of the proposedscraper blades are mounted at spaced apart positions of the sucker rodstring as it is assembled and lowered into the oil well. Each of saidparaffin scraper tools are coaxially mounted on a particular length ofsucker rod with the movement of a particular scraping toolbeing limitedto alternation between upper and lower stop means mounted on a length ofsucker rod. The manner in which the several items of equipment areintegrated into a system of apparatus is illustrated in FIGS. 6, 7, 8and 12 of the Drawings and should be readily self evident fromexamination of said figures in the light of the descriptive material inthe foregoing disclosure.

The several scraper tools can be co-axially mounted on and ride up anddown on the sucker rod line all during the pumping operation and therandom agitation of the plurality of slidable scraper tools will preventbuild up of paraffin and asphalt deposits to some extent. It should beremembered that sucker rods also become coated with deposits andeventually stick to deposits on the walls of the oil well tubing 30 andit should be noted that the paraffin scraper structures disclosed hereinscrape both the sucker rod and the walls of the oil well tubing as thescrapers move up and down. If a dent or crooked spot develops in eitherthe sucker rod string or the oil well tubing so that the sucker rods ruband damage the walls of the tubing, one of the spaced apart slidablescrapers will eventually get impacted between the suckerr'od line andthe walls of the tubing at the point of the damage. In such position,the impacted paraffin spacer will function as a self positioningcentering spacer so that the rub wear damage is transferred from theexpensive oil well tubing to the less expensive sucker rod and scrapertool offering another feature of protective utility.

It will be appreciated that the mere random agitation motion of theplurality of scraper tools as pumping action and oil flow occurs willproduce only a minor amount of preventive buildup of paraffin andasphalt deposits. When serious clogging of the well begins to load thepumping" action of the sucker rod line in spite of the minor agitationof the string of plural scrapers, the operator will suspend pumping andlift the sucker rod line through several feet of upward pull at thesurface until the sucker rodline is lifted off of the bottom of thewell. This lifting action will drag the sucker rod line and each of theplurality of attached scraper tools upward through a considerabledistance of tubing and the suspended sucker rod line will now weighseveral thousand pounds. The operator then drops the sucker rod line andthe collective weight of the suckerv rod line is driven or hammeredagainst the centering collars of the several paraffin scraper toolsmounted on sucker rod line when the stop means and connective rod boxesof the sucker line strike the top collars of the scraper tools. Thisaction drives the several scraper tools through the corrosive depositson the walls of the tubing scraping and cutting loose said deposits.This operation of lifting and dropping the sucker rod line andassociated plurality of scraper tools mounted therein can be repeated asoften as necessary to break up the deposits and looosen the friction ofpumping the sucker line.

Much of the scraped off paraffin and deposits will flow upward with thepumped crude oil flow passing through the open spaces of the scrapertools. However, when pumping action in the well is suspended and crudeoil ceases to flow upward both the scraper tools and the broken upparticles of paraffin will start settling back toward the bottom of thewell. However, the metal scraper tools are heavier than the particles ofparaffin and will settle faster than the paraffin. When the scrapertools settle against the lower cone shaped' seat stop means thecombination of the cone shaped seat stop means plus the mass of thescraper ring will block off the tubing and prevent any further sinkingof the paraffin particles that are floating in the crude oil.

When pumping is resumed the upflow of oil will drive A the smallslidable scraper tools away from the seat valves and the upflow of oiland paraffin particles to the surface will be continued.

In spite of all of this preventive and delaying action the interior ofthe oil well tubing will eventually become so coated with obstructivedeposits that more se rious cleaning and overhall of the well will benecessary. At such time the operator will pull the entire sucker rodline to the surface for cleaning. As the operator pulls the sucker rodline each of the plurality of scraper tools thereon will set down ontheir lower seat valve stops and each scraper tool will successively andrepeatedly scrape the tubing walls as each is pulled to the surface.Since scraped off particles of paraffin and asphalt cannot get past thenow closed seat valve stop means, the deposit particles trapped betweenthe spaced apart scrapers will be pulled to the surface and emptied inincrements. The thoroughness this cleaning action with the aid of thesimple scraper tools and associated apparatus disclosed herein can delaythe drastic necessity of pulling and cleaning the oil well tubing forsuch an extended period of operation to as to more than pay for the costof this simple system of scraping and cleaning. Many low grade marginalwells that are now abandoned because of clogging excesses of paraffinand asphalt deposits make the cost of cleaning the well by presentmethods excessive in comparison to the small low flow recovery may wellprove to have a further period of useful and profitable life with theaidof the simple scraping and cleaning apparatus disclosed by thisinvention.

ADVANTAGES OF THE INVENTION A material advantage of the invention isthat it provides for a simple, durable and inexpensive paraffin scrapingand removal tool that can be semipermanently installed on the oil wellsucker rod string and remain in place and. semioperative concurrentlywith pumping production and instantly available for more drasticscraping and cleaning action when needed thereby minimizing the expenseand down time normally involved in pulling .the oilwell tubing forcleaning purposes.

Another advantage of the invention lies in having devised aninexpensively manufactured and nearly indestructable paraffin scrapingtool thatwill have no moving parts to break off, that will be soimpervious to wear by semi-permanent installation and usage as to makeit practical for the operator to install a plurality of said paraffinscraping tools in an oil well and leave them in place.

A further advantage of the invention is found in having provided aparaffin scraper tool that can be left in the well semi-permanentlyduring pumping operations so as to provide continuous agitation andscraping action in order to prevent the build up of paraffin or asphaltdeposits before stubborn tenacious deposits have formed.

Still another advantage of the invention disclosed herein lies in havingdevised a sturdy, simple, inexpensive and almost indestructable paraffinscraper tool and associated apparatus that can rise through a limiteddistance with the up-flow of oil through the oil well tubing or bygravity fall by its own weight through a limited distance but with meansfor supplemental hammer driving of the scraper tool by lifting ordropping the weight of the sucker rod line through an extended pistonstroke so as to drive the upper and lower stop means against the top orthe bottom of the scraper tool.

A still further and somewhat unexpected side advanta'ge of thisinvention lies in having provided a paraffin scraping tool of suchsubstantial structure as to have use-value in hammering out dents in thewalls of the oil well tubing by using the weight of the sucker rodstring to drive the scraper tool through the dented area in the tubing.

Another advantage of the invention derives from having devised a simplescraper tool that can simultaneously scrape both the sucker rod line andthe inside surfaces of the oil well tubing. A further advantage of .theparaffin scraper tool provided by this invention resides inthe fact thatbecause of its concentric design it can often function as a means ofspacing and centering the moving sucker rods within the oil well tubingso as to prevent frictional wear and damage to the oil well tubing.

Another advantage of the invention is that oil well tube walls may bescraped and cleaned while in place in the ground, eliminating thenecessity of puling the tube for cleaning purposes.

Still another advantage of the invention is that well tubing is cleanedand scraped by either upward (extractive) or downward (insertive) motionof the sucker rod-scraping tool mechanism and drastic scraping andcleaning action can be initiated by simply increasing the length of thepiston stroke of the sucker rod line. A material advantage of theparaffin scrapers disclosed by this invention is that they can beinstalled with insertion of the sucker pumping rod string and remainrelatively inert or passive during regular pumping operations but alsobe available for standby readiness for immediate initiation of scrapingand cleaning action when needed without the excessive down timecustomarily required for the temporary insertion of leased commercialscraping and cleaning equipment before the cleaning operation can bestarted. This availability of continuous or frequent scraping ofparaffin and asphalt restricts the thickness of contaminating depositsto within a workable range so that pumping interruptions for majoroverhaul and reconditioning of the well with the expense of contractservice specialists being held to a minimum.

Although this specification describes but a single embodiment of theInvention with certain applications thereof, it should be understoodthat structural or material rearrangements of adequate or equivalentparts, substitutions of equivalent functional elements and othermodifications in structure can be made and other applications devisedwithout departing from the spirit and scope of our Invention. Wetherefore desire that the description and drawings herein be regarded asonly an illustration of our Invention and that the lnvention be regardedas limited only as set forth in the following claims.

Having thus described my invention, I claim:

1. A double ended freely slidable paraffin scraping and removing toolfor continuing cleaning and maintenance of the interior surfaces of oilwell tubing, with the tool designed to providescraping action whenmoving either up or down, said paraffin scraper tool comprising, incombination:

A. a pair of freely slidable annularly shaped aligning and centeringguide collars mounted back to back in spaced relationship:

1. each of said aligning and centering guide collars being fabricatedfrom a short length of metal tubular material,

2. with the outside circumference of said tubular guide collars beingsubstantially similar in size than the inside circumference of standardoil well tubing, and

3. a guide hole aperture provided through each of said tubular aligningand centering guide collars having an inside diameter slightly largerthan the diameter of the sucker rod being employed in the oil well;

B. a connective paraffin scraping ring;

1. having an exterior structural appearance like that of a short lengthof thick metal tubing,

2. having an exterior circumference of such size as to frictionallyengage and scrape the interior walls of one of the standard sizes of oilwell tub- 3. with the inside circumference of said connective paraffinscraping ring being substantially larger than the circumference ofsucker rods normally employed in oil well drilling and pumpingoperations such as to permit oil and dislodged paraffin particles topass through said scraper ring even when a moving sucker rod is inplace, and

4. with said connective paraffin scraping ring being mounted between therear ends of the pair of oppositely disposed annularly shaped aligningand centering guide collars and welded to the outside rear surfaces ofeach of the annularly shaped aligning and centering guide collars; and

C. a plurality of vertical slots cut into both ends of said connectivetubular paraffin scraper ring with said slot openings being cutfrom thetubular material from which the connective paraffin scraping ring isfabricated, such that: I 1 1. the open space slots form a plurality ofscraping surfaces and flow ports permitting the flow of oil and paraffinparticles through said scraper ring, while the i 2. tubular materialbetween said vertical slot exit ports form a plurality ofcircumferentially spaced apart vertical spacer legs in continuingalignment with the interior and exterior tubular surfaces of theparaffin scraping ring, and

3. the bottom edge surfaces of each of said vertical slots near thecenter of said connective paraffin cutting blade being designated as thescraper edge surfaces;

said double ended scraper tool being designed to ride and move freely upand down between spaced apart stop means on an oil well sucker rod suchthat paraffin particles are scraped off of the interior walls of oilwell tubing by any up or down movement of the double ended paraffinscraper tool.

2. The improved and simplified double ended tool for scraping andremoving paraffin from the inside surfaces of oil well tubing asdescribed in claim 1 together with the addition of arcuate cuttingblades cut into the scraper edge surface at the bottom of each of saidvertical slots of the said connective tubular scraping ring to provideboth cutting and scraping action against the inside walls of the welltubing being cleaned with said cutting and scraping action beingprovided by any up or down movement of the scraper tool.

3. Av double-ended freely slidable paraffin scraping and removing toolfor continuing maintenance of the interior surfaces of oil well tubing,comprising, in combination:

a. ring means including a tubular ring having two spaced ends forcutting and shaping paraffin, and arranged for frictionally engaging andscraping interior walls of standard oil well tubing while being spacedfrom a sucker rod disposed within the tub ing, the spacing between thering means and sucker rod permitting oil and dislodged paraffinparticles to pass through the ring even when the sucker rod is in place;

b. guide means connected to the ring means and extending in oppositedirections from spaced ends of the ring means and arranged between thering means and sucker rod for cooperating with the sucker rod andaligning and centering the ring means relative to the sucker rod; and

c. passage means forming open space slots between the ring means andguide means for permitting the flow of oil and paraffin particles aroundthe guide means and through the ring means; the doubleended scraper toolbeing designed to ride and move freely up and down between spaced apartstop means provided on an oil well sucker rod such that paraffinparticles are scraped off of the interior walls of oil well tubing byany up-and-down movement of the double-ended paraffin scraper tool.

1. the open space slots form a plurality of scraping surfaces and flowports permitting the flow of oil and paraffin particles through saidscraper ring, while the
 1. having an exterior structural appearance likethat of a short length of thick metal tubing,
 1. each of said aligningand centering guide collars being fabricated from a short length ofmetal tubular material,
 1. A double ended freely slidable paraffinscraping and removing tool for continuing cleaning and maintenance ofthe interior surfaces of oil well tubing, with the tool designed toprovide scraping action when moving either up or down, said paraffinscraper tool comprising, in combination: A. a pair of freely slidableannularly shaped aligning and centering guide collars mounted back toback in spaced relationship:
 2. with the outside circumference of saidtubular guide collars being substantially similar in size than theinside circumference of standard oil well tubing, and
 2. The improvedand simplified double ended tool for scraping and removing paraffin fromthe inside surfaces of oil well tubing as described in claim 1 togetherwith the addition of arcuate cutting blades cut into the scraper edgesurface at the bottom of each of said vertical slots of the saidconnective tubular scraping ring to provide both cutting and scrapingaction against the inside walls of the well tubing being cleaned withsaid cutting and scraping action being provided by any up or downmovement of the scraper tool.
 2. tubular material between said verticalslot exit ports form a plurality of circumferentially spaced apartvertical spacer legs in continuing alignment with the interior andexterior tubular surfaces of the paraffin scraping ring, and
 2. havingan exterior circumference of such size as to frictionally engage andscrape the interior walls of one of the standard sizes of oil welltubing,
 3. A double-ended freely slidabLe paraffin scraping and removingtool for continuing maintenance of the interior surfaces of oil welltubing, comprising, in combination: a. ring means including a tubularring having two spaced ends for cutting and shaping paraffin, andarranged for frictionally engaging and scraping interior walls ofstandard oil well tubing while being spaced from a sucker rod disposedwithin the tubing, the spacing between the ring means and sucker rodpermitting oil and dislodged paraffin particles to pass through the ringeven when the sucker rod is in place; b. guide means connected to thering means and extending in opposite directions from spaced ends of thering means and arranged between the ring means and sucker rod forcooperating with the sucker rod and aligning and centering the ringmeans relative to the sucker rod; and c. passage means forming openspace slots between the ring means and guide means for permitting theflow of oil and paraffin particles around the guide means and throughthe ring means; the double-ended scraper tool being designed to ride andmove freely up and down between spaced apart stop means provided on anoil well sucker rod such that paraffin particles are scraped off of theinterior walls of oil well tubing by any up-and-down movement of thedouble-ended paraffin scraper tool.
 4. with said connective paraffinscraping ring being mounted between the rear ends of the pair ofoppositely disposed annularly shaped aligning and centering guidecollars and welded to the outside rear surfaces of each of the annularlyshaped aligning and centering guide collars; and C. a plurality ofvertical slots cut into both ends of said connective tubular paraffinscraper ring with said slot openings being cut from the tubular materialfrom which the connective paraffin scraping ring is fabricated, suchthat: